1. Field
The following description relates to a technology for optical communications, and more particularly, to a large capacity optical transceiver module for optical communications.
2. Description of the Related Art
Internet data is continuously increasing with the use of smartphones, tablet PCs, cloud services, and the like. Further, Ethernet signals for the Internet are also becoming high speed and high capacity. After standardization of 10 gigabit (G) Ethernet in 2002, 40G Ethernet and 100G Ethernet were standardized in 2010, and more recently, an optical transceiver module for transmitting 100G Ethernet optical signals has been commercially introduced. As such, 100GBASE-LR4 standard is used, in which four optical signals having a wavelength at a rate of 25 Gb/s are multiplexed into 4×25 Gb/s to transmit 100G Ethernet signals up to 10 kilometers through a single mode fiber (SMF).
In a transceiver module for transmitting 100 G Ethernet optical signals, four electric signals at a rate of 25 Gb/s are input to the inside of a module, to be recovered by a clock and data recovery (CDR), amplified through a laser diode driver (LD driver), and converted into optical signals in a laser diode (LD). The four electric signals are converted into optical signals having LAN-WDM wavelengths of, for example, 1295.56 nm, 1300.05 nm, 1304.58 nm, and 1309.14 nm, which are standardized by IEEE, and wavelength-division multiplexing of the signals is performed through an optical MUX, such that the signals are transmitted as one optical fiber.
In a receiver, if an optical signal having four wavelengths is input, the optical signal is divided per wavelength, and optical to electrical converted and amplified by a photo detector (PD) and a transimpedance amplifier (TIA), to be output as an electric signal. The output electric signal is recovered in a CDR, and is output to the outside of an optical transceiver module. For miniaturization of the optical transceiver module, four LDs and one optical MUX are integrated into one transmitter optical sub-assembly (TOSA), and four PDs and four TIAs are integrated into one receiver optical sub-assembly (ROSA).
Meanwhile, 400G Ethernet is not yet standardized, and an optical transceiver module is not commercialized either. As a method for transmitting 400G Ethernet signals, multiplexing of 16 signals at a rate of 25 Gb/s is generally expected. In this case, 16 LDs and one optical MUX are expected to be integrated into one TOSA, and 16 PDs, 16 TIAs and one optical DMUX are expected to be integrated into one ROSA.
However, with the capacity of an optical transceiver module becoming larger, the number of channels to be optically multiplexed by wavelength division multiplexing is increased, and the number of channels to be integrated is also increased. As the number of channels is increased, the number of LDs and PDs to be integrated into one TOSA and ROSA is also increased, thereby increasing the number of packaging processes and level of packaging, and resulting in a higher risk of defects in manufacturing. Further, even a defect in any one chip, which occurs in the course of manufacturing, is considered a failure of the overall optical transceiver module, thereby reducing mass productivity.